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Using IEC 61850 Analogue GOOSE Messages for OLTC Control of Parallel Transformers. Goran Leci, Končar-Power Plant and Electric Traction Engineering Inc., Croatia. Zoran Gajić, ABB SA Products, Sweden. Samir Aganović, ABB SA Products, Sweden. Josip Benović, TSO (HEP), Croatia.
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Using IEC 61850 Analogue GOOSE Messages for OLTC Control of Parallel Transformers Goran Leci, Končar-Power Plant and Electric Traction Engineering Inc., Croatia Zoran Gajić, ABB SA Products, Sweden Samir Aganović, ABB SA Products, Sweden Josip Benović, TSO (HEP), Croatia Sergio Gazzari, ABB Croatia
1. Introduction2. Parallel control (circulating current method)3. Automatic tap changer controller (ATCC)4. Inter IED communication (GOOSE messages) 5. Conclusion
1. Introduction • Automatic voltage control can be either for single transformer or for parallel transfomers • Voltage automatic control function is designed to • maintain service voltage at the LV side of a PT within given limits around a set target voltage Uset • Voltage control function measures the magnitude of the LV side busbar voltage UB and compares it to the Uset
Voltage scale for control actions • If the voltage UB is measured to be outside the • deadband (U<U1 or U>U2), command sequence starts and after time delay has elapsed, appropriate raise or lower command will be issued
Introduction • Parallel control of PTs means control of two or more PTs • connected to the same busbar on LV side • Parallel control can be made by three alternative methods: • - reverse reactance method, • - master-follower method*, • - circulating current method* • * Requires communication among the voltage control functions on the • PTs in parallel group
2. Parallel control with the circulating current method • PT with a higher no-load voltage on LV side (higher tap • position) will produce circulating current, while other one • with lower no-load voltage will receive circulating current • When load is put on the PTs, the circulating current will • remain the same, it will be superimposed on the load • current in each PT
Parallel control with the circulating current method • Circulating current method aims to minimize the circulating • current at the given voltage target value and ensures total • reactive load is shared between parallel PTs in proportion • to their rating
Parallel control with the circulating current method • Method requires extensive exchange of data between • the voltage control functions • Summary of required signals to be communicated for • circulating current method: • - measured busbar voltage, • - measured transformer current (real and imaginary parts), • - voltage set point, • - blocked status, control in manual, timer on ...
3. ATCC installation • Two 20 MVA, 110/20 kV, YNd5 transformers with OLTC • Each PT has dedicated IED with integrated protection • and control functions • Automatic control of parallel transformers is done by • circulating current method (∆Isinɸ) • Information exchange between voltage control functions • for PTs in parallel are done by GOOSE messages • in accordance with IEC 61850 standard
ATCC installation IEC 61850-7-4 defines 91 logical nodes divided into 13 groups:
S/S 110/20 kV Donji Andrijevci – ATCC installation RET670 87T, 87N, 50/51, 50N/51N, 49, 90 (ATCC), 84 (YLTC) REB500 BU 21T, 50/51 REX521+SPAZC402 50N/51N
Logical nodes ATCC and YLTC • ATCC represents regulator itselfs and integrates • funcionality like: • - voltage measurement and supervision, • - timing, line drop compensation, • - circulating current measurement and supervision etc. • YLTC represents OLTC mechanism and integrates • funcionality like: • - tap position reading, • - OLTC mechanism supervision, • - issuing of the manual and automatic raise and lower • commands
4. Inter IED comm. between voltage control functions • GOOSE message is contained by: • - single point status of binary inputs or outputs, • - double point status of control apparatus, - analogue values (measured voltage, currents, ...) • IEDs send GOOSE messages periodically and multicast in predefined intervals on data change inside associated dataset
Inter IED comm. between voltage control functions • IEDs contain GOOSE control blocks with associated datasets • containing XCBR and CSWI which the voltage control function • needs for single/parallel operation
Inter IED comm. between voltage control functions • Complete exchange of voltage control function data, • analog as well as binary, is made by GOOSE messages
Inter IED comm. between voltage control functions • Voltage control block will send the same dataset, but each of them • will have unique address definitions for GOOSE control block
5. Conclusion • For parallel transformer application, we used circulating • current method (requires comm. between voltage control • functions in parallel group) • Chosen comm. interface is GOOSE interbay communication • based on IEC 61850-8-1 • Since September 2007 three S/Ss with such control are • infull operation and all engineering process is done by • Končarengineers with Croatian TSO and ABB help